TECHNICAL FIELD
[0001] The present invention relates to a method of producing an implant implantation guide
for implanting a dental implant (artificial tooth root) and, particularly, to a method
of producing an implant implantation guide by utilizing a CAD/CAM system and to a
guide block to be used in the producing method.
BACKGROUND ART
[0002] Dental implant (artificial tooth root) treatments are widely utilized in the dental
field. In order to improve the functionality (occlusal balance) and the aesthetic
appearance of an artificial tooth to be fitted on a dental implant and to stably maintain
the dental implant in a jawbone, it is important to properly design the implantation
position and the implantation direction (implantation angle) of the dental implant
through a diagnosis, and precisely implant the dental implant based on the design.
[0003] In recent years, an attempt is made to properly determine the implantation position
and the implantation direction of the dental implant through a diagnosis utilizing
a three-dimensional medical image obtained by CT imaging and produce an implant implantation
guide for effecting the implantation position and the implantation direction determined
through the diagnosis by means of a CAD/CAM system for clinical application (see,
for example, Patent Documents 1 and 2).
[0004] However, it is difficult to produce a highly precise implant implantation guide that
permits accurate positioning of the dental implant in an oral cavity based on CT imaging
data alone. This is because: the CT imaging data includes data of several-hundred-micron
voxels; a metal fixture attached to a tooth causes a noise called "metal artifact"
in the image; a prosthetic device composed of a non-imageable material such as a resin
cannot be imaged; the imaging range, the imaging depth and the size and shape of the
image vary depending on CT values; and the three-dimensional image formed based on
the CT imaging data has a simplified shape with reduced geometrical and dimensional
accuracies.
[0005] In other words, the implant implantation guide produced based on the CT imaging data
is not as precise as that produced based on a dental arch model formed of a plaster
(a dental arch model of a plaster obtained by taking an impression of a dental arch
in a patient's oral cavity).
Patent Document 1: Japanese Unexamined Patent Publication No. 2003-245289
Patent Document 2: Japanese Unexamined Patent Publication No. 2001-170080
DISCLOSURE OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0006] It is difficult to produce the highly precise implant implantation guide based on
the CT imaging data alone. Therefore, it is conceivable to substitute data obtained
from the highly precise dental arch model for a corresponding data portion of the
three-dimensional image formed based on the CT imaging data, and produce the implant
implantation guide based on the substituted data by means of the CAD/CAM system. However,
it is necessary to scan the dental arch model to obtain geometrical data of the dental
arch model. Disadvantageously, the data obtained by the scanning is less precise than
the original dental arch model at this stage. Further, it is difficult to eliminate
an error occurring when the image is correlated with the model data for the substitution.
[0007] In view of the foregoing, it is a principal object of the present invention to provide
a method of producing a highly precise implant implantation guide for safely and precisely
performing a dental implant treatment.
MEANS FOR SOLVING THE PROBLEMS
[0008] According to the present invention, there is provided a method of producing an implant
implantation guide for CAD/CAM, the method including the steps of: (1) preparing a
guide block including an attachment portion to be fitted on a dental arch of a patient,
and a processing portion having a mark of a processing reference coordinate system
required for processing; (2) acquiring patient's CT image data with the guide block
being fitted on the patient's dental arch; (3) transforming information of an implant
implantation position and an implant implantation direction (implantation angle) determined
through diagnosis on a three-dimensional image formed based on the CT image data into
coordinate information based on the processing reference coordinate system on the
guide block; and (4) setting the guide block in a cutting processor, and cutting the
guide block into a guide shape that reflects the coordinate information based on the
processing reference coordinate system.
[0009] The attachment portion of the guide block is preferably composed of a non-imageable
material, and the processing portion of the guide block is preferably composed of
an imageable material.
[0010] According to the present invention, there is provided a method of producing an implant
implantation guide for CAD/CAM, the method including the steps of: (1) separately
preparing a guide base including an attachment portion to be fitted on a dental arch
of a patient and an imaging marker specifying at least three points, and a processing
portion attachable to the guide base; (2) acquiring patient's CT image data with the
guide base being fitted on the patient's dental arch; (3) providing a guide block
by attaching the processing portion to the guide base for unification; (4) transforming
information of an implant implantation position and an implant implantation direction
(implantation angle) determined through diagnosis on a three-dimensional image formed
based on the CT image data into coordinate information based on a processing reference
coordinate system to be utilized for processing the processing portion via a coordinate
system defined by the imaging marker; and (5) setting the guide block in a cutting
processor, and cutting the guide block into a guide shape that reflects the coordinate
information based on the processing reference coordinate system.
[0011] According to the present invention, there is provided a guide block for use in the
implant implantation guide producing methods described above, the guide block including
an attachment portion to be fitted on a patient's dental arch, and a processing portion
having a mark of a processing reference coordination system required for a cutting
process.
[0012] According to the present invention, the processing portion of the guide block is
composed of an imageable material.
EFFECTS OF THE INVENTION
[0013] According to the present invention, the guide block is first prepared. The guide
block unitarily includes the processing portion to be milled (cut) into a predetermined
shape in a step to be described later, and the attachment portion for attaching the
processing portion to the patient's dental arch.
[0014] The attachment portion is, for example, a dental impression of a plaster or the like
directly taken from the patient's oral cavity, or formed to conform to the patient's
dental arch. Therefore, when the guide block is thereafter worn by the patient, the
attachment portion is perfectly fitted on the patient' s dental arch without displacement
in the oral cavity.
[0015] With the guide block being fitted in the patient's oral cavity, the patient's oral
cavity is imaged through the CT imaging to provide CT image data.
[0016] The image data thus provided is a three-dimensional image including images of patient's
jawbones, a patient's dental arch, a patient's tooth deficient site and the like.
The three-dimensional image also includes an image of the processing portion of the
guide block fitted in the patient's oral cavity. That is, the image data includes
raw image data of the patient as well as image data of the guide block.
[0017] The implant implantation position and the implant implantation direction (implantation
angle) are determined on the three-dimensional image through the diagnosis. The implantation
position and the implantation direction (implantation angle) are defined, for example,
in the form of a straight line on the three-dimensional image.
[0018] The straight line representing the implantation position and the implantation direction
(implantation angle) is data based on a three-dimensional image display coordinate
system.
[0019] On the other hand, the guide block is processed based on the processing reference
coordinate system defined on the processing portion of the guide block in the guide
block cutting step to be described later.
[0020] The data indicating the implant implantation position and the implant implantation
direction (implantation angle) determined through the diagnosis on the three-dimensional
image based on the three-dimensional image display coordinate system is transformed
into the data based on the processing reference coordinate system.
[0021] Then, the guide block is set in the cutting processor, and cut into the guide shape
that reflects the implant implantation position and the implant implantation direction
(implantation angle) obtained through the transformation based on the processing reference
coordinate system, i.e., that reflects the data of the implant implantation position
and the implant implantation direction, by the CAD/CAM system.
[0022] An implant implantation guide thus produced by the cutting process is configured
such that the attachment portion to be fitted on the dental arch has a shape conformal
to the dental arch model. Therefore, when the implant implantation guide is fitted
in the patient's oral cavity, the implant implantation guide is perfectly fitted on
the patient's dental arch without a gap. Thus, the implant implantation guide is free
from wobble in the patient's oral cavity, and serves as a guide for forming a hole
for implantation of the dental implant in the patient's oral cavity.
[0023] The implant implantation guide produced by the inventive producing method is properly
fitted on the dental arch in the patient's oral cavity without wobble in the patient's
oral cavity.
[0024] Since the implant implantation guide is properly and precisely fitted in the patient's
oral cavity, a dental treatment can be properly performed on the patient with reference
to the guide.
[0025] In the present invention, the guide base and the processing portion of the guide
block may be provided as separate members rather than as a unitary member. Where the
patient who wears the guide block has a smaller mouth or suffers from a sensitive
vomiting reflex, it is often difficult to fit the guide block in the patient's oral
cavity for the CT imaging. In this case, it is desirable to use the guide block including
the guide base and the processing portion provided as separate members. This is because
the guide base is a smaller and thinner member including the attachment portion and
the imaging marker, thereby alleviating a burden on the patient who wears the guide
base during the CT imaging.
[0026] By utilizing an existing technique, the imaging marker specifying the at least three
points on the guide base makes it possible to transform the data based on the three-dimensional
image display coordinate system into the data based on the processing reference coordinate
system with the use of the coordinate system defined by the three points.
[0027] The inventive guide block is advantageously used for a dental implant surgery on
the patient.
[0028] Particularly, where the processing portion of the guide block is composed of the
imageable material, the implant implantation guide is produced by processing the guide
block, and then the CT imaging is carried out with the implant implantation guide
being fitted in the patient's oral cavity for confirmation. Thus, a guide surface
of the implant implantation guide is clearly imaged. As required, the implant implantation
guide may be modified with reference to the resulting image.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029]
Fig. 1 is a diagram illustrating a dental arch model of a plaster to show a method
of producing an implant implantation guide according to one embodiment of the present
invention.
Fig. 2 is a perspective view illustrating an exemplary processing portion 11 to show
the implant implantation guide producing method according to the embodiment of the
present invention.
Fig. 3 is a diagram showing the implant implantation guide producing method according
to the embodiment of the present invention, particularly, for explaining a method
of producing a guide block 10 from the dental arch model.
Fig. 4 is a diagram showing the implant implantation guide producing method according
to the embodiment of the present invention, particularly, for explaining the step
of acquiring CT image data.
Fig. 5 is a diagram illustrating an exemplary three-dimensional image based on the
resulting CT image data to show the implant implantation guide producing method according
to the embodiment of the present invention.
Fig. 6 is a diagram showing the implant implantation guide producing method according
to the embodiment of the present invention, particularly, for explaining how to carry
out a coordinate transformation.
Fig. 7 is a diagram showing the implant implantation guide producing method according
to the embodiment of the present invention, particularly, for explaining the cutting
of the guide block 10.
Fig. 8 is a perspective view illustrating an exemplary implant implantation guide
100.
Fig. 9 is a diagram for explaining another exemplary guide block 10 to be used for
the implant implantation guide producing method according to the embodiment of the
present invention.
DESCRIPTION OF REFERENCE CHARACTERS
[0030]
10: GUIDE BLOCK
11: PROCESSING PORTION
12: ATTACHMENT PORTION
50: CUTTING PROCESSOR
52: CUTTING MACHINE
100: IMPLANT IMPLANTATION GUIDE
BEST MODE FOR CARRYING OUT THE INVENTION
[0031] Specific embodiments of the present invention will hereinafter be described with
reference to the drawings.
[0032] Figs. 1 to 7 show a method of producing an implant implantation guide according to
one embodiment of the present invention.
[0033] First, a dental arch model of a patient who is to be subjected to an implant treatment
is produced. The production of the dental arch model is achieved, for example, by
taking a patient's dental impression with a plaster by a conventionally known method.
[0034] Fig. 1 shows the dental arch model thus produced. The dental arch model faithfully
replicates a lower dental arch on a patient's lower jaw. In the dental arch model,
three left molar teeth are missing by way of example.
[0035] The dental arch model may replicate a dental arch which is restored with dummy teeth
DT1, DT2, DT3 of an imageable material (e.g., aluminum, apatite or the like) disposed
at deficient sites. The dummy teeth DT1, DT2, DT3 replicate teeth to be disposed at
the deficient sites in a proper arrangement as having proper sizes. In order to maintain
the replicated teeth in this state, artificial tooth roots (dental implants) for supporting
the replicated teeth are required. Therefore, the implantation positions and the implantation
directions of the dental implants for the replicated teeth are determined through
diagnosis in a step to be described later.
[0036] The step of positioning the dummy teeth at the deficient sites in the dental arch
model is not necessarily required, but the subsequent step may be performed without
positioning the dummy teeth in the dental arch model.
[0037] Next, a guide block 10 to be fitted on the dental arch model is produced. The guide
block 10 includes a processing portion 11 and an attachment portion 12. As shown in
Fig. 2, the processing portion 11, for example, has a rectangular plan shape and a
predetermined thickness h (as measured vertically), and is composed of an imageable
material (e.g., aluminum, apatite or the like).
[0038] The processing portion 11 has, for example, a corner C0 defined by three orthogonal
edges. These three edges are defined as X-, Y- and Z-axes on the processing portion
11. The X-, Y- and Z-axes define a processing reference coordinate system for processing
the processing portion 11.
[0039] The attachment portion 12 serves to attach the processing portion 11 to the dental
arch model. The attachment portion 12 is composed of a non-imageable material such
as an acryl resin (see Fig. 3).
[0040] The processing portion 11 is positioned with respect to the dental arch model. For
example, the processing portion 11 is positioned generally horizontally with respect
to the dental arch model as covering the deficient sites. In order to fix the position
of the processing portion 11 with respect to the dental arch model, an acryl resin
gel is filled in a space defined between a lower surface of the processing portion
11 and the dental arch model, more specifically, in a space inside the dental arch,
and properly shaped.
[0041] The filled acryl resin is solidified with time to serve as the attachment portion
12. The solidified acryl resin is bonded to the lower surface of the processing portion
11 to be unified with the processing portion 11. On the other hand, the solidified
acryl resin is not bonded to the dental arch model, but is removable from the dental
arch model. The attachment portion 12 of the acryl resin thus solidified and removed
from the dental arch model has an attachment surface that is conformal to the geometry
of the inner side of the dental arch.
[0042] Where the dummy teeth are disposed in the dental arch model in this case, the dummy
teeth may be covered with the acryl resin and contained as a part of the attachment
portion 12 in the guide block 10.
[0043] Referring to Fig. 4, the guide block 10 produced by utilizing the dental arch model
is removed from the dental arch model after the acryl resin 12 is solidified. The
removal of the guide block 10 is facilitated, for example, by preliminarily applying
a releasing agent or the like onto the dental arch model. Then, the removed guide
block 10 is fitted in the patient's oral cavity.
[0044] The attachment portion 12 of the guide block 10 is conformal to the dental arch model
prepared based on the patient's oral cavity and, particularly, the attachment surface
of the attachment portion 12 is conformal to the geometry of the inner side of the
dental arch. Therefore, the guide block 10 is perfectly fitted in the patient's oral
cavity without wobble.
[0045] With the guide block 10 being fitted in the patient's oral cavity, the CT imaging
is carried out to provide CT image data. A three-dimensional image of the patient's
oral cavity formed based on the resulting CT image data is shown in Fig. 5.
[0046] The three-dimensional image shown in Fig. 5 is displayed on a display of a computer
system. The three-dimensional image can be rotated in a desired direction. Further,
a slice of a desired portion can be displayed. With this arrangement, an optimum implant
implantation position and an optimum implant implantation direction (angle) are determined
on the three-dimensional image through diagnosis.
[0047] Meanwhile, the implant implantation position and the implant implantation direction
(implantation angle) determined on the three-dimensional image through the diagnosis
are data specified based on a three-dimensional image display coordinate system.
[0048] For example, it is herein assumed that the implant implantation positions and the
implant implantation directions (implantation angles) are specified on the three-dimensional
image as shown in Fig. 6.
[0049] In Fig. 6, the three-dimensional image is displayed based on the display coordinate
system (X0, Y0, Z0). Points a1, b1, a2, b2, a3, b3 for specifying the implant implantation
positions and the implant implantation directions are represented based on the display
coordinate system (X0, Y0, Z0) as follows:
a1=(x0a1, y0a1, z0a1)
b1=(x0b1, y0b1, z0b1)
a2=(x0a2, y0a2, z0a2)
b2=(x0b2, y0b2, z0b2)
a3=(x0a3, y0a3, z0a3)
b3=(x0b3, y0b3, z0b3)
[0050] A line segment extending between the points a1 and b1 is represented as follows:

[0051] On the other hand, an image 11' of the processing portion 11 of the guide block 10
is also shown in the three-dimensional image of Fig. 6. The corner C0 is also shown.
In the three-dimensional image of Fig. 6, the coordinates of the corner C0 are represented
as follows:
C0=(x0c0, y0c0, z0c0)
The X-, Y- and Z-axes defined by the three edges of the processing portion 11 as extending
through the corner C0 are also defined based on the three-dimensional display coordinate
system (X0, Y0, Z0).
[0052] That is, the coordinates (X, Y, Z) are represented as follows:
(X, Y, Z)=(θCOX0+C0, θCOY0+C0, θCOZ0+C0)
wherein θCO is a difference between X0 and X, between Y0 and Y or between Z0 and Z.
[0053] Thus, in the three-dimensional image, the implant implantation positions, the implant
implantation directions (implantation angles), the position of the corner C0 of the
processing portion 11 of the guide block 10 and the orientation of the processing
portion 11 (directions of the X-, Y- and Z-axes) are defined as data based on the
three-dimensional image display coordinate system.
[0054] Next, the data based on the three-dimensional image display coordinate system is
transformed into data based on the processing reference coordinate system defined
by the corner C0 of the processing portion 11 of the guide block 10 and the X-, Y-
and Z-axes.
[0055] The transformation is carried out, for example, in the following manner.
[0056] Provided that the coordinates of the origin are represented by (Xc0, Yc0, Zc0) in
the processing reference coordinate system on the guide block 10, the coordinates
of the origin are represented by (X0c0, Y0c0, Z0c0) in the three-dimensional display
coordinate system.
[0057] On the other hand, provided that coordinates associated with the implant implantation
positions and the implant implantation directions (implantation angles) determined
on the three-dimensional image through the diagnosis are represented by (X0a1, Y0a1,
Z0a1) on the three-dimensional image, the coordinates (based on the three dimensional
display coordinate system) are transformed into coordinates based on the processing
reference coordinate system in the following manner:
(X0a1, Y0a1, Z0a1)×(Xc0, Yc0, Zc0)÷(X0c0, Y0c0, Z0c0) =(Xa1, Ya1, Za1)
[0058] Next, as shown in Fig. 7, the guide block 10 is set in a cutting processor 50, and
fixed in position by a fixing device 51. Then, the guide block 10 is processed into
a shape such as to guide the dental implants by a cutting machine 52.
[0059] In the cutting process, the reference coordinate system on the guide block 10 and
the coordinate data of the implantation positions and the implantation directions
based on the reference coordinate system (obtained through the transformation) are
provided, so that the cutting machine 52 can automatically cut the guide block 10
into a shape such as to properly guide the dental implants. The cutting may be carried
out semi-automatically, semi-manually, or manually with reference to the data, rather
than automatically.
[0060] The resulting guide block 10 serves as the implant implantation guide 100.
[0061] Fig. 8 illustrates one example of the implant implantation guide 100. The implant
implantation guide 100 includes a generally U-shaped portion 11' produced by processing
the processing portion 11 and covering the dental arch, guide grooves G1, G2, G3 formed
in the U-shaped portion 11' and an attachment portion 12.
[0062] The guide grooves G1, G2, G3 are each dimensioned such as to guide a drill (a drill
shaft or a bar), serving as a drill (drill shaft or bar) guide groove. Alternatively,
the guide grooves G1, G2, G3 may each serve as a head guide groove for guiding a head
of a hand piece in which the drill is chucked (a groove having a greater size than
the drill guide groove).
[0063] The attachment portion 12 of the implant implantation guide 100 to be fitted on the
dental arch is composed of the acryl resin. The attachment portion 12 is perfectly
fitted on the patient's dental arch without a gap or a play. Therefore, the implant
implantation guide 100 fitted on the patient's dental arch makes it possible to properly
drill implant implantation holes at the positions previously determined through the
diagnosis in the patient's jawbone. That is, the drill is operated according to the
implant implantation guide 100, whereby the implant implantation holes can be properly
and speedily drilled in the directions at the positions previously determined through
the diagnosis. Then, the dental implants are implanted at these positions.
[0064] In the aforementioned embodiment, the processing reference coordinate system for
the processing of the processing portion 11 of the guide block 10 is defined by the
single corner C0 and the three edges defined as the three orthogonal lines. However,
how to define the processing reference coordinate system for the processing of the
processing portion 11 is not limited to the aforementioned method.
[0065] For example, as disclosed in Japanese Patent Application No.
2004-334936 previously filed by the applicant of the present invention, a processing reference
plane or a processing reference coordinate system may be defined based on three points
preliminarily specified.
[0066] In this case, the processing portion 11 is not necessarily required to be composed
of the imageable material, but may be composed of a material such that the at least
three points are imageable on the CT image.
[0067] More specifically, the processing portion 11 of the guide block 10 may be configured
such that, when the processing portion 11 is imaged through the CT imaging to provide
CT image data, the at least three points required for defining the processing reference
plane or the processing reference coordinate system are shown on the three-dimensional
image formed based on the resulting CT image data. For example, the processing portion
11 may be entirely composed of the non-imageable material, and the three points required
for specifying the position of the processing portion 11 may be composed of an imageable
material. Alternatively, straight lines required for defining the processing reference
coordinate system may be drawn with an imageable material on the processing portion
11.
[0068] In the embodiment described above, the guide block 10 prepared for the production
of the implant implantation guide includes the processing portion 11 and the attachment
portion 12 provided as a unitary member. However, at the initial stage, the processing
portion 11 and the attachment portion 12 of the guide block 10 may be provided as
separate members.
[0069] Fig. 9 illustrates the guide block 10 having such a structure.
[0070] Referring to Fig. 9, a guide base (resin base) 12 serving as the attachment portion
is fitted on the dental arch model of the plaster. The guide base 12 is composed of,
for example, an acryl resin (non-imageable material), and unitarily includes an imaging
marker 114 including at least three balls 111, 112, 113. The three balls 111, 112,
113 each have an imageable member which defines a center thereof.
[0071] The processing portion 11 may have the same construction as that described with reference
to Fig. 2. For example, the processing portion 11 has a rectangular plan shape and
a predetermined thickness h, and is composed of an imageable material (e.g., aluminum,
apatite or the like).
[0072] The guide base (resin base) 12 including the imaging marker 114, and the processing
portion 11 having the processing coordinate system required for the processing are
separately prepared, and only the guide base (resin base) 12 is fitted in the patient's
oral cavity. Then, the CT imaging is carried out to provide the CT image data.
[0073] If it is difficult to fit the guide block 10 shown in Fig. 3 in the patient's oral
cavity because the patient has a smaller mouth or suffers from a sensitive vomiting
reflex, the fitting of the resin base 12 shown in Fig. 9 alleviates a burden on the
patient during the CT imaging.
[0074] In this case, the imaging marker 114 including the at least three balls 111, 112,
113 is provided unitarily with the resin base 12, so that a relationship between a
marker coordinate system defined by the three centers of the three balls 111, 112,
113 and the processing reference coordinate system of the processing portion 11 to
be attached after the imaging can be determined by means of a three-dimensional measurement
apparatus by utilizing an existing technique. Therefore, information of the implant
implantation positions and the implant implantation directions determined on the CT
image through the diagnosis can be transformed into the coordinate information required
for the processing of the processing portion 11 of the guide block 10 via the marker
coordinate system defined by the imaging marker 114. The coordinate information is
used for cutting the guide block 10 through CAD/CAM.
[0075] The present invention is not limited to the embodiments described above, but various
modifications may be made within the scope of the present invention defined by the
following claims.